No matter the time or context, inter-religious dialogue is rarely a simple endeavour. Throughout history, occasions on which Christians and Muslims have met have unfortunately most often been ones of tension, conflict and misunderstanding - a situation which, in many places, is little improved today. And yet, more than one thousand years ago, in and around the currently volatile cities of Basra and Baghdad, Christians and Muslims lived side by side in a context where they were able to debate openly and defend their respective faiths, resulting in an awareness and understanding of each other’s traditions which is largely unparalleled in today’s world.

The period in question is that of the early ninth century C.E., barely two centuries after the expansion of the Islamic Empire, which by that point stretched from Southern Spain in the West to the borders of China in the East. In doing so, it incorporated a number of native Christian populations, who remained the majority for a number of centuries, and who provided essential skills to their Arab conquerors, with many Christians being employed as physicians, bureaucrats and translators. Indeed, under the patronage of the ruling caliphs, it was Christians who were responsible for transmitting Greek philosophical thought into Arabic and Islamic thinking. It is in this context that we find the first generation of Christian theologians who wrote in Arabic, and who were faced with explaining Christian beliefs and practices in a language closely intertwined with Islam and the Qur’an.

From the texts available to us, it is evident that Christians felt the need to defend a number of elements of their faith, one of the most fundamental being that of their expression of God as Trinity; that is to say Father, Son and Holy Spirit. For their Muslim counterparts, whose central tenet was that of tawhīd (declaring the oneness of God), the idea of the divine being as one God in three persons or hypostases was completely unthinkable.

At the same time that Christians were looking for ways to explain the Trinity to their Muslim neighbours, an internal Islamic debate was taking place, which centred on the nature of God and His ninety-nine ‘beautiful names’ (ʾasmāʾ allāh al-Ḥusnā). These names are considered to be the names of God revealed to Muhammad in the Qur’an, and are accordingly given as a list of nouns, such as; ‘The Living’, ‘The Knowing’, ‘The Wise’. Some Muslims began to question what these names actually meant, both semantically and metaphysically speaking. Were they purely nominal, that is to say were they simply empty terms which pointed to God Himself and therefore identical with Him? Or should they be conceived of as real meaningful characteristics or entities present alongside God? The Christian theologians, who were clearly deeply involved in Islamic society, witnessed this internal debate taking place and saw the opportunity to use it in order to explain the doctrine of the Trinity in a way that their Muslim counterparts might understand. The way they achieved this was to say that if Muslims accept that God is ‘speaking’ and ‘knowing’, then they must accept that He has ‘word’ and ‘life’. This, they state, is what the Christians mean when they talk about God as Father, Son and Holy Spirit: His ‘word’ is the Son and His ‘life’ the Holy Spirit. Whilst they did not succeed in persuading their opponents to accept the doctrine, the exchanges they experienced provides the twenty-first century reader with much to take away.

Although these representatives of the two faiths were engaged in polemic against one another, what one can see is that both groups are asking similar questions about the nature of God, and having very similar internal as well as external debates, even though the final outcomes are different. In the context of interfaith dialogue today, this observation is highly important.

Early attempts at inter-religious dialogue were geared towards finding common ground. The Second Vatican Council (1965) issued a declaration about Muslims, stating that it has respect for Islam and listing a number of common features between Christianity and Islam such as belief in one God and reverence towards Jesus. This highlighting of similarities, however, whilst being a positive first step, can only achieve so much. For as soon as members of different faiths reach a fundamental difference (for example, Jesus being the Word and Son of God for Christians, and no more than a human prophet for Muslims) those in 'dialogue' either come to an impasse or attempt to 'paper over the cracks', as it were, by ignoring fundamental and important differences between their two faiths.

Recently, however, a significant shift has been taking place, whereby dialogue increasingly involves recognising each other’s differences and accepting them. In order to do this one has to put oneself in the shoes of the other and understand their faith in its own terms, not looking in from the outside, or viewing the other as holding a distorted version of one's own beliefs. A huge part of this endeavour requires understanding how the other person came to hold a certain belief: the processes they went through, questions they asked, possibilities they dismissed, and so on. Only then do we begin to see that actually we are not that different at all: we are all trying to answer the same questions and achieve the same goals. And this is exactly what the Christian and Muslim scholars of ninth century Iraq were doing, genuinely attempting to understand the beliefs of the other. They may not have come to an agreement; yet their deep awareness and appreciation of one another allowed them to live side by side for centuries in relative harmony.

The message for us today, over a millennium later, is clear. Yes, we may ultimately have different beliefs, but at least in understanding another's journey we are able to be more accepting of his or her destination - something which is applicable to all faiths, societies and belief-systems.